Localized momentum sources in a transport code as a model for biased-rings in a Helicon plasma
T. Marine, M. Breyfogle, A.S. Ware, M. Gilmore, C. Watts, E. Schuster
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Dallas, Texas, November 17-21, 2008
Abstract
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In the HELCAT experiment, biased concentric rings are used as control
elements for the radial electric field profile. By varying the bias
voltages, the local E×B flow can be modified. Here, we investigate
modeling the biased rings as localized momentum sources in a 1-D
transport code. The effect will be identical to a source of E×B flow
in the limit of zero β (i.e., when diamagnetic flows are negligible).
By varying the momentum sources a sheared radial electric field can be
generated that can suppress turbulent particle and heat transport. The
results of modeling typical HELCAT experimental equilibria will be
presented along with an investigation of the density dependence of
ion-electron thermal coupling. We will also test the impact of different
numerical models for the momentum sources and compare the results with
experimental measurements of the radial electric field in the HELCAT
experiment.